| In the course of screening for naturally occurring insecticides from the northwest plants in China, some insecticidal plants were found and one of them was Macleaya microcarpa, which belongs to the Papaveraceae family, Macleaya genera. Aiming at to clarify the chemical compounds and their insecticidal activities of M. microcarpa, the dissertation focused particularly on isolation and identified of insecticidal compounds from M. microcarpa, and ascertained the main insecticidal composition of M. microcarpa. To further verify the bioactivities and mechanism of the main insecticidal composition, the toxicity action against several normal insects were investigated under the laboratory conditions, toxicity symptom and some effect of important physiological and biochemical criteria of insects were carried out. Moreover, the antifungal activities of M. microcarpa against plant-pathogenic fungal were also investigated. The main results and conclusions were given as follows:1. To verify the bioactive spectra and action of total alkaloids from Macleaya microcarpa, the insecticidal activities of the alkaloids were investigated in the laboratory against the third instar larvae of Mythimna separata, fifth instar larvae of Pieris rapae, third instar larvae of Plutella xylostella, third instar larvae of Helicoverpa armigera, and adults of Myzus persicae, Schizaphis graminum, Sitophilus zeamais, Tribolium castaneum, Tetranychus viennensis and Tetranychus cinnabarinus. The results indicated that the total alkaloids from M. microcarpa demonstrated the AFC50 values of antifeedant (48 h) were 0.265, 0.557 and 0.543 mg/mL respectively and the LC50 values of stomach poison (96 h) were 0.106, 0.123, 0.166 mg/mL respectively against the larvae of M. separata, P. rapae and P. xylostella. The alkaloids also showed strong contact activity against M. persicae and S. graminum, and the LC50 values (48 h) were 0.362 and 0.710 mg/mL, respectively. The toxicity activities of the alkaloids against T. viennensis were higher than that of T. cinnabarinus with the LC50 values (24 h) were 0.185 and 0.754 mg/mL respectively. The alkaloids had a strong population inhibition effect on S. zeamais and T. castaneum. The growth inhibition percentage against third instar larvae of H. armigera treated with the alkaloids (5 mg/mL) was about 69.5% (7 d). Moreover, egg hatch and larval survival of M. separata were only 58.8% and 22.6%, respectively, at the day five after treatment with the alkaloids at a concentration of 2.5 mg/mL, which were significantly lower than those of the control and other treatments.2. Appling chromatography technology and insecticidal activity tracing, 21 compounds were isolated from the chloroform extracts of M. microcarpa. Chemical construction of 16 of them were identified with authentic samples or spectrum technology, including 8 alkaloids: norsanguinarine, dihydrosanguinarine, dihydrochelerythrine, 6-acetonyl-dihydrosanguinarine, berborine, 6-methyl–dihydrochelerythrine,β-allocryptopine and protopine, 3 triterpenoids:oleanolic acid, ursolic acid and lupeol, 2 fatty acids: 19-tricosednoic acid, 18-docosenoic acid, 1 sesquiterpenoid: eudesm-4-ene-3-ol and 2 other compounds:β-sitosterol and stigmasterol. Among them, 2 triterpenoids: ursolic acid and lupeol, 2 fatty acids: 19-tricosednoic acid, 18-docosenoic acid, and 1 sesquiterpenoid: eudesm-4-ene-3-ol were obtained from macleaya for the first time, and 2 alkaloids: norsanguinarine and 6- methyl– dihydrochelerythrine were firstly isolated from M. microcarpa. Insecticidal and antifeedant activities of isolated compounds were assayed against the larvae of M. separata, P. rapae, Plutella xylostella and H. armigera. The results showed that alkaloids and sesquiterpenoids from the plant had higher activity than other compounds. The insecticidal activity of dihydrosanguinarine was higher than that of other active compounds, which may be the main insecticidal active ingredient of M. microcarpa. The LC50 values of stomach poison (96 h) against the third instar larvae of M. separata, fifth instar larvae of P. rapae and third instar larvae of P. xylostella were 0.085, 0.065 and 0.215 mg/mL respectively. The corrected mortalities were 51.57% and 81.48% (5 mg/mL) respectively against third instar larvae of H. armigera after day five and seven treatment. The sesquiterpenoid eudesm-4-ene-3-ol had also insecticidal activity against the third instar larvae of M. separata and the fifth instar larvae of P. rapae, the AFC50 values of antifeedant (48 h) against the third instar larvae of M. separata and LC50 value of stomach poison (96 h) against the fifth instar larvae of P. rapae and the third instar larvae of P. xylostella were 0.305, 0.345 and 0.587 mg/mL respectively. The dissertation discussed to conclusion that alkaloids were main insecticidal compounds of M. microcarpa, and other sesquiterpenoids, triterpenoids may also devoted to the insecticidal activities of extracts of the plant. Moreover, further research should be carried out on insecticidal compounds and activities of M. microcarpa.3. The insecticidal activity of dihydrosanguinarine to the fifth larvae of M. separata was tested with the method of the leaf disc bioassay, and its effects on the activities of AChE and ATPase in central nerve system and esterase , carboxyl esterases (CarE), phosphatase, glutathione S-transferase (GSTs) and the O-demethylase activity of cytochrome P450 in fifth instar larvae of the M. separata Walker were investigated. The results indicated that the stomach toxicity LD50 value (72 h) of dihydrosanguinarine against the fifth instar larvae of M. separata was 0.259 mg/mL. The inhibition rates of AChE were 11.78%, 18.21%, 35.27% and 40.31% respectively at 12, 24, 48 and 72 h of exposure time. In vitro, the IC50 of AChE was 0.0274 mg/mL. It had no significant influence on the activity of Na+, K+-ATPase and Ca2+, Mg2+-ATPase. The activitives of esterase and CarE in insects tested had no distinct change. With treatment time extending, the activitives of acid phosphatase (ACP) in insects tested were gradually inhibited by dihydrosanguinarine. The change of alkaline phosphatase (AKP) activity was very complex; The GSTs and O-demethylase activity of cytochrome P450 was inhibited by dihydrosanguinarine. The results suggest that AChE may be one of important targets of dihydrosanguinarine.4. The antifungal activity of alkaloids from Macleaya microcarpa in vitro and in vivo was tested so as to reveal its antifungal activity. The bioassay results indicated that the alkaloids inhibited mycelial growth of 16 species investigated plant-pathogenic fungal in vitro. It especially could markedly inhibitted the mycelial growth to Botrytis cinerea and Rhizoctonia cerealis. Their EC50 value against B. cinerea and R. cerealis were 0.022 mg/mL and 0.024 mg/mL, respectively. The spore germination EC50 value against B. cinerea and Alternaria alternata were 0.039 mg/mL and 0.049 mg/mL, respectively. In addition,protective effect and therapeutic effect of the alkaloids (0.75 mg/mL) against the B. cinerea were 73.68% and 43.06% on tomato, respectively. Finally protective effect and therapeutic effect of the alkaloids against the Erysiphe graminis were 63.36% on wheat in potted. The dissertation preliminarily clarified the bioactive spectra and action of M. microcarpa against insects, and the types and insecticidal activities of chemical compounds from M.microcarpa, and few new natural products and insecticidal compounds were found. The insecticidal activities of active compounds were investigated and dihydrosanguinarine may be the main insecticidal active ingredient from M. microcarpa. The systematic research on insecticidal action of dihydrosanguinarine showed its insecticidal spectrum and actions, which verified the possible bioactivities and mechanism of dihydrosanguinarine against the larvae of M. separata. What's more, the antifungal activities of M. microcarpa against plant-pathogenic fungal were also investigated and the antifungal spectrums were confirmed. This finding was a basis of utilizing M. microcarpa and exploiting new botanical pesticide.
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